Update diagrams links

docs/00-series-overview.md

@@ -198,7 +198,7 @@ Where possible, theoretical discussions are accompanied by practical material, i
 
 The objective is to connect high-level architecture with practical implementation.
 
-Available now: [PlantUML diagrams and SVG previews](../diagrams/readme.md) and a [C++ A/B trial boot simulation](../examples/simulations/ab-trial-boot/readme.md). Raspberry Pi and QEMU demonstrations are planned.
+Available now: [PlantUML diagrams and PNG previews](../diagrams/readme.md) and a [C++ A/B trial boot simulation](../examples/simulations/ab-trial-boot/readme.md). Raspberry Pi and QEMU demonstrations are planned.
 
 ---
 

docs/03-system-architecture.md

@@ -47,7 +47,7 @@ These are roles, not a shopping list of separate services. One tool may cover se
 
 The following view shows the roles and the server/device boundary for the system-update example used in the next chapter.
 
-![OTA roles and device boundary](../diagrams/rendered/ota-architecture.svg)
+![OTA roles and device boundary](../diagrams/rendered/ota-architecture.png)
 
 [PlantUML source](../diagrams/plantuml/ota-architecture.puml)
 

docs/04-starting-an-updated-system-or-service.md

@@ -101,7 +101,7 @@ Returning to a previous version is called **rollback**. Keeping A available make
 
 The state diagram separates an explicit health-check failure from a startup failure that prevents the checks from running. It also shows the checks after returning to A.
 
-![A/B trial boot and recovery](../diagrams/rendered/ab-trial-boot.svg)
+![A/B trial boot and recovery](../diagrams/rendered/ab-trial-boot.png)
 
 [PlantUML source](../diagrams/plantuml/ab-trial-boot.puml) · [Runnable simulation and failure scenarios](../examples/simulations/ab-trial-boot/readme.md)
 

docs/05-storage-layout.md

@@ -66,7 +66,7 @@ Two slots on one storage device also do not protect against failure of that whol
 
 The following diagram adds access responsibilities to the logical layout. A is running while the installer prepares B. Trial requests and confirmation use the platform's boot control interface.
 
-![A/B storage areas and access responsibilities](../diagrams/rendered/ab-storage-layout.svg)
+![A/B storage areas and access responsibilities](../diagrams/rendered/ab-storage-layout.png)
 
 [PlantUML source](../diagrams/plantuml/ab-storage-layout.puml) · [Simulation of saved boot state across resets](../examples/simulations/ab-trial-boot/readme.md)